Had this happen to me once, though totally my own fault. Was brewing kombucha, and left it out in the bottles a little too long before burping.

Me standing there, kombucha and peach slices pulverized against the cap, kombucha leaving a large mark on the ceiling it all happened so fast, glad I was wearing my glasses.

No injuries except my pride, but it did take some hours to clean up.

I wouldn't do it in a thermos, but I guess those are mostly accidents?

It was bramble beer for me. Put a load of lovely ripe brambles in a batch of homebrew beer, one of the little pithy bits on the inside wedged up against the bottom of the airlock, and overnight the pressure built up enough to pop the cork out and spray the ceiling with brambly splats and beer.

Tasted okay though.

My mate brewed his bramble beer by putting his brambles through a juicer and only adding the juice and pulp, because he's cleverer than me and has a certain amount of foresight.