One of the most memorable demos from high school science class involved inflating a balloon with hydrogen and then lighting it on fire. Predictably (oh, the humanity), the thing exploded in a sudden burst of flame, and made a loud noise that scared people three classrooms over.
Periodic Videos has taken things a bit further by cooling a hydrogen-filled balloon in a bath of liquid nitrogen. Here's the funny thing: The cooler balloon made a quieter "bang!" than a typical room-temperature balloon. What's up with that?
If you have five minutes, this video explains the effect through a series of experiments, and is a lovely example of
science in action. Enjoy:
Bonus footage and discussion: