Foam bubbles are created when air is dispersed into a liquid containing surfactants.  AB-type surfactants quickly migrate to the newly formed air–water interface, orienting their hydrophilic heads in the water and hydrophobic tails toward the air, which lowers surface tension and allows bubbles to form.

As the bubble film (lamella) drains and thins under gravity, the local surfactant concentration changes along the surface.  This creates surface tension (surface pressure) gradients that drive a counterflow, often called the Marangoni effect, pulling liquid and surfactant back into the thinning regions.

This self-correcting movement helps reconstitute the film and stabilize the bubble, preventing it from rupturing too quickly.