"Time for another crazy experiment - this time, exploding hot air balloons?! Look out!"
In the episode, Shayne and Nick create a balloon filled with hydrogen gas that will explode in a similar manner to that of the Hindenburg.
By mixing a solution of sodium hydroxide and lye with aluminum, the reaction gave off hydrogen gas, an element lighter than air, but also much more flammable.
When Shayne placed the match next to the balloon, it not only popped the rubber exterior, but caused the hydrogen to react with the flame, creating a fireball.