Perhaps puffed is a better word than popped. While it is true that puffed rice is currently made using large pressure swings, people online claim rice has been

Perhaps puffed is a better word than popped. While it is true that puffed rice is currently made using large pressure swings, people online claim rice has been puffed using "hot salt frying" (https://en.wikipedia.org/wiki/Hot_salt_frying https://en.wikipedia.org/wiki/Hot_salt_frying) for hundreds of years (https://nitter.net/whetstone_mag/status/1564282053025210368?lang=en https://nitter.net/whetstone_mag/status/1564282053025210368?..., https://en.wikipedia.org/wiki/Puffed_rice https://en.wikipedia.org/wiki/Puffed_rice) and supposedly there is a secondary source dating this practice to 1886 at the absolute latest, about two decades before the invention of the modern production method. This method seems like a reinvention of hot sand frying. They would probably expand better if they were soaked in water prior to puffing.