SJ’s Gas under pressure experiment – When batter is poured into a pre-heated pan the outside starts cooking straight away. The liquid from the milk and egg evaporate i.e turn into gas. The gas presses against the outside layer but cannot get inside thus the outer layer inflates like a balloon hence the popover (aka Yorkshire Pudding) has a crispy outside and is light and fluffy inside.
Enjoyed this video? Why not check out one of these next!