Why does my food go boom in the microwave?

[Zaqiqu]

Popcorn aside, whenever I put something in the microwave for only a few seconds longer than I probably should have, it pops. I just watched a rib-bone go flying out of its slab, meat spewing everywhere. Is heat responsible for this action?

 

[HallsofIvy]

Any thing you cook in a microwave contains water. In fact, that is how a microwave works, heating the water in the food which then cooks the food. The pops you hear are the water vaporizing inside a closed space and "rupturing" it.