Water goes boom in microwave

Sure enough, water can "explode". I was heating 3 or 4 ounces of water in a juice glass in the microwave. I was tending to some other matter (and I'd forgotten about the water) when I heard what sounded like someone loudly clap-popping a medium plastic bag of air. "What was THAT?" Spinning around and seeing the microwave, I peered in and saw the glass was nearly empty. What was most fascinating to me (besides finding out personally that my water can blowing up in the microwave) was seeing how evenly distributed the water droplets were on the walls and ceiling of the microwave. The glass was still whole.

I remember reading about this phenomenon a few years ago. The writeup had suggested that water could be ready to explode (my words) and just waiting for the glass to be jiggled to release the energy. Makes me that more willing to poke my superheated coffee with a spatula behind the safety of my welding mask.