When it came time to take the lasagna out, I moved the skillet over and forgot to turn off the burner. The lasagna in the glass casserole dish was set on the hot burner. About 6 minutes later, the thing EXPLODED - sending hot cheese and shards of glass all over both of us.
That happened to my mom once! We were sitting the the living room, and all of a sudden, BOOM! We looked at each other... then realized what had happened. It was crazy... fortunately no one was in the kitchen at the time.
I can't really think of any disasters off hand (though I do think this is an awesome idea for a thread). But once, a few years ago, my mom was cooking and she decided (at random) to give me a lesson on what to do if the stove ever caught fire. Right as she stopped speaking... the stove caught fire! Of course she put it out promptly and no one was hurt! Crazy!