I have noticed that there is lots of tiny air bubbles in the fuel line between the fuel filter housing and the fuel pump. (mechanics.stackexchange.com)
When it's ready, it will be covered with tiny air bubbles and doubled in size. (staceyhomemaker.com)
Then the whites of eggs, an elastic substance that forms thousands of tiny air bubbles when beaten, are whipped to just the right stiffness and folded into the mixture. (si.com)