> I wonder what about the design makes it a rocket compared to what I would assume is a pretty standard design?

Injuries nonwithstanding, the quality of the seal means it was an exceptionally well designed item for the purpose of storing 99% water.

side note: there's a reason you get a visit from the FBI if you buy ten pressure cookers (e.g. if you find a great Black Friday deal and have a large family and plan Christmas gifts...)

The pressure build up can be quite a lot from fermentation. I’ve accidentally fermented drinks in glass swing top bottles. And upon attempting to open the bottle the pressure ripped the stopper and the metal parts right off the bottle at high speed.

If you were purposely fermenting something, you could build enough pressure to pop the bottle.

Thermos jars have interior threads for an inner plug and an exterior thread(singular) for the cosmetic cap that doubles as a drinking cup. Maybe there's a condition where the external cup would be holding the inner plug from releasing, and then upon removing the cap, the entire lip starts tapering outward and lets go of the plug without gradually relieving pressure.

(to be fair, I don't think an externally threaded cap will solve this problem. If the thread held to a higher pressure, then the core part of the plug will eventually blow out even more energetically. An overpressure vent port is still necessary)

I'm guessing pressure is not allowed to escape before it's on the last thread.