There's the product
Every now and then some friends and I will get some dry ice, a bunch of plastic bottles and other containers with a screw-on lid and have a laugh making small explosions.
Basically you take a bottle, fill it 1/4 with water and 1/2 with dry ice and screw the cap on. You then have around a minute before it explodes.
A 1/2 liter coke bottle will make a nice whooompf and a 20 liter plastic gasoline can (the largest we have tried) will make a bang that can be heard maybe half a mile away. They very rarely sizzle out, and the ones that do probably have a defect, or we didn't get the cap screwed on properly. There's some time pressure, so you don't stand around checking before you throw the container. I would imagine that a metal container will make a pretty big bang (higher pressure before it ruptures) and may throw out some nasty debris.
It's good fun!
That may no longer hold, since 20oz bottles feel flimsier these days and all have low-profile caps. Haven't tried in a while.
Also, PVC pipe burried in ground, drop dry ice bomb in, drop another bottle with some water in it on top = dry ice mortar. Those little plastic bubble things that toys in vending machines come in? A little dry ice, a little water, close it, place lid down. POP, the bubble part flies a meter or so in the air.
I will note for anyone trying this that the parent's ratios are very different from what I used. Crushed dry ice to 1/10-1/8 full, about twice that much water. Unusually warm water (say, from near the surface of a pond or lake in late August) will greatly reduce time-to-boom, so beware. Too little water and it'll freeze before boom, greatly delaying or even preventing it. Very annoying. Attaching to something heavy (but NOT shrapnel-genrating) and sinking in ~5-10 feet of water is fun. Huge bubble, explosion can be felt on land nearby.
It may be the case for a typical water bottle but thermoses have much larger caps. The maximal force that a cap can hold is proportional to its perimeter (~r), the force itself is proportional to the area of the cap (~r^2) and the pressure. So larger caps can blow off by lower pressure. I would bet that for a thermos the weak point is the cap.
+1 - I'm always up for a good explosion video!
Most often though, if you fill up the bottle with too much nitrogen, it won't explode. It'll just freeze up and slowly disperse through whatever cracks are present. If it didn't explode over night, it probably wouldn't have at all.
I suspect it might have started to fizzle due to air leaving the bag, or due to a small leak, which is pretty harmless. Nitrogen explosions of half-litre bottles are very large, and can shake the ground 20-30m away. I can test it later today if time permits and upload a video, but overall, it would've been much clearer if it went off.
Edit: to people saying the cap is the weak point: 9/10 times it's the bottom that gives in first.