The problem with sprinking herbs on the top, would be that the container of water can be superheated at the bottom and not superheated at the top. (In fact, the top tends to be much cooler than the bottom, because of evaporation.)
Popcorn doesn't pop particularly well in the microwave oven. The bag the popcorn is in has a little metal patch to make it work better. You can't just throw popcorn in the microwave and pop it. Hot air poppers and popping corn in hot oil work better.
Popcorn pops because it has a tough shell and a little spot of moisture in the center of the kernel. If ...
Popcorn should be considered one of "nature's little miracles" - & a way to make a huge profit out of air.
Yes, you can pop other dried grains/seeds, but don't expect anything quite so bag-filling as maize.
Quinoa, chia, sorghum & amaranth will all pop [in a dry pan, not sure about microwave]