An explosion is something that's usually over by the time you notice it. But thanks to high-speed cameras, we can better understand this complex chemical reaction and its powerful effects.
Using a clear potato cannon and high speed cameras that can capture frames at rates 1000x faster than a regular camera, the explosion that simply happens can be slowed down to the point where you can see the spark igniting the air/fuel mixture and propagating thru the chamber - as well as all its complex behavior as fresh air rushes in and tries to equalize the pressure as the hot air is expelled and the projectile is, well, projected.
Besides experiencing with different ignition points, it's fascinating to keep in mind this is precisely the same sort of thing that happens hundreds of times per second, inside our cars' combustion engines! :)