Ever have Soup Explode in the Microwave?

I was heating up a bowl of clam chowder in the micro, covered with a paper plate, like I've done more times than I can count. Suddenly it goes *POOF* popping off the plate and spewing clam chowder all over the inside of the microwave. After cleaning up the mess I heated what was left in a kettle on the stove. WTF?