Sometimes when I am kneading my dough I can feel some of the air bubbles popping. Is this a bad thing? Does this mean I am kneading it to long? Every were I have looked it says it is important to have air bubbles in your dough. I always use both the poke test and window test. The bread usually turns out ok. I'm just not sure why this happens sometimes.
This is completely normal and actually what you want bread dough to do, the bubbles mean that your yeast is active, and your bread will rise. However, bubbles that are too big can be undesired in your finished product and may actually cause the bread to cook unevenly. I make sure to eliminate all large bubbles during each kneading session. The presence of these bubbles means that you have a fair amount of gluten developed in your dough, which will ensure you get a light fluffy and well risen result.