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My partner, dissatisfied with raggedy poached eggs, found an alternative method. Most likely on Facebook :P

Break an egg into a glass, add a little water, microwave until cooked.

The first attempt resulted in perfectly shaped, but particularly unsatisfying, part cooked eggs with runny whites.

Today I thought I would have a go, nuking them for a bit longer.

Four eggs, four glasses, a bit of water in each. I opened the door to check after 1:30 and it wasn't quite enough to cook all the white. I added 10 seconds and as I opened the door to check, hilarity struck with a loud pop, including all over me.

An extra breakfast job...

What might have caused an egg to explode?

I have a couple of theories

  1. The white at the top cooked and formed a seal, the rest of the egg expanded below it
  2. The membrane around the yolk was strong enough to hold until the pressure got too much (unlikely I think)
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    The directions that came with my silicon egg poaching cups say to poke the yolks with a toothpick before microwaving.
    – user73902
    Aug 15 at 13:40
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    Thanks @B.Goddard, but if you watch the video from kutykwyfer, that is done and doesn't help.
    – Steve
    Aug 15 at 21:09
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    I learned this would happen from Zak McKracken, a 1988 video game. (youtu.be/vVkrfXya_OM?t=391) Aug 17 at 14:25
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    @DanielDarabos yes! to keep the air stewardess occupied while you steal the air tank from the overhead locker, right? (and yet I can barely remember last week..)
    – Aaron F
    Aug 17 at 15:22
  • A key piece of information is how you placed the items on the turntable. Did you place things on the center so they spin, or slightly away from the center so they travel in a circle? If the former, then I'd expect heating to be uneven, and a superheated area would be unsurprising. Aug 17 at 19:18
32

Oh lordy. You're lucky you didn't get hurt. Ann Reordan did a good video about these microwave egg hacks. The segment with her many experiments starts around 6:00. (other hacks/myths are at the beginning and end of the video.)

https://youtu.be/vdaKrT9x1Zc

Short version: it's speculated that the microwave super-heats the interior of the egg and the internal steam pressure causes the explosion. Occasionally eggs will also pop dramatically in a frying pan, but not as often.

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    Wow. Thanks for that. She is great the way she systematically tests various ideas to come to a conclusion
    – Steve
    Aug 15 at 4:12
  • 1
    This. Most recipe hack videos are faked and Ann's breakdown of them makes it really easy to spot inconsistencies in the wild. Basically don't try a recipe from any cooking video that uses stylized, sped up footage or a lot of fast cuts. Some people have seriously hurt themselves trying to recreate the fake recipes at home.
    – interduo
    Aug 17 at 22:35
  • It would be helpful to include in your answer that 1) entire eggs, 2) only egg whites and 3) only egg yolks all explode in the microwave. There are many claims and "hacks" circulating the internet that nuking only the yolk is perfectly safe, which Ann clearly proves to be a lie. But not everyone is going to watch her video if they believe to already know a valid solution.
    – Elmy
    Aug 18 at 6:00
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In 2017 researchers from Charles M. Salter Associates in San Francisco looked into the exploding microwaved eggs. They'd been hired to offer testimony in litigation of a case where a consumer claimed an exploding egg had damaged his hearing, so their focus was on how loud the eggs were, but they also offered a possible explanation as for the reason of the explosions; quoting from the article on Live Science ( https://www.livescience.com/61109-why-microwave-eggs-explode.html ),

If you stick a potato in the microwave without piercing its skin first, steam pressure can build up under the skin and cause the potato to detonate. That's a simple mechanism for an explosion, the researchers wrote, similar to a grenade going off and shattering the device's outer shell.

But a hard-boiled egg doesn't have a skin with the high tensile strength of a potato's, and an eggshell — designed for a baby bird to peck through — isn't strong enough to contain high internal steam pressure. There is a membrane between the white of an egg and its shell that might allow pressure to build up, but that comes off when you shell an egg and shelled eggs still pop.

The researchers suggested an alternative explanation.

The yolk of an egg, they discovered with their meat thermometer, heats up much faster than the surrounding water. Perhaps, they reasoned, tiny pockets of water are getting trapped inside the proteins and getting superheated.

At normal air pressure, those pockets would have room to expand and turn into steam. But inside an egg, pressure from surrounding, hardening proteins might be forcing the pockets to remain liquid even as their temperatures climb.

But disturb one of those pockets, let it expand, and the water molecules would rush to fill the void — expanding, disrupting the surrounding tissue, and allowing any other pockets to flash through a phase change at the same time. The resulting collective bubble-bursting would tear the egg to bits, flinging the pieces far and wide in a way that might resemble a more typical explosion under pressure.

"To an observer, the egg appears to have exploded," the researchers wrote in the paper, but, "it is probably more accurate to describe the phenomenon as a rapid boiling of superheated water."

So it appears as though tiny pockets of water become trapped within the hardening egg. These pockets become superheated as they are under pressure from the surrounding proteins, until the pockets burst open, causing a mess in your microwave (and flinging scalding water into your face if you open the microwave door first).

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    Dear Live Science: A potato in a microwave does not "detonate". It explodes.
    – Vikki
    Aug 15 at 19:43
  • 2
    @maxathousand Explosion is the more general term that includes subsonic and supersonic events. Unless you're talking about car engines, current usage restricts detonation to the result of high explosives creating supersonic shockwaves. Historically detonation meant a literal or figurative loud explosion but that broader usage appears to be a thing of the past. Aug 16 at 15:14
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    @maxathousand: Yes and no. The colloquial dictionary definition of "detonate" is just "explode". But it also has a more specific technical meaning (en.wikipedia.org/wiki/Detonation) - a type of combustion involving a supersonic exothermic front accelerating through a medium ... (as opposed to deflagration like in black powder / other slower explosives where the combustion front is subsonic). (Thanks, Mythbusters :). Anyway, with no combustion, no detonation; even in more casual colloquial usage it has the wrong connotations. Aug 16 at 17:27
  • 3
    @maxathousand to be fair, I upvoted Vikki's comment thinking I knew the difference in the definitions, and didn't at all. I thought detonating was the act of triggering an explosion ‾\_('_')_/‾ the more you know
    – TCooper
    Aug 16 at 21:52
  • 2
    @PeterCordes: Strictly-speaking, the supersonic exothermic shock front does not have to involve chemical combustion (example, other example), but few people are ever likely to experience a non-chemical detonation.
    – Vikki
    Aug 16 at 22:55

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