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?