Videos of a Chinese popcorn making technique are doing their rounds on the internet. While, for many, popcorn popping has a unique rhythm to it that trickles from a single popping kernel to a deluge of pings and pops; in China, popcorn pops with a bang.
This video shows the popcorn “hammer” at work, and as soon as the people here the boom, they flock in closer with their pots and pans to buy some popcorn:
Ah, it's all coming back to me now, my childhood in China during the 1980's. It was always the same old man on a trike, and the throng of children who was there as much for the popcorn as for the little explosions and clouds of escaping steam. Each little plastic bag sold for 10 cents, and for 50 cents he will pop a whole can with the corn or rice that you brought yourself. It always amazed me that a couple of litres of corn at the bottom of a sack would fill it to the brim after popping.
And in that same video, a commenter explains the science behind the technique:
Popcorn pops because the pressure on the inside exceeds the pressure on the outside of the hull. Heating it inside a sealed container forces the pressures to be equal until the door is opened and the pressure on the outside of the hull drops dramatically, making all the kernels pop at the same time. Simple science/engineering.
Maybe the boom works as advertising: hear it and come get freshly popped popcorn. However, in case you missed the bang, maybe the wailing car alarms will help:
The technique was also spotted in Japan, only this time, instead of making popcorn they puffed rice: