When a droplet of water falls on a hot pan, it dances across the surface, skimming on a thin layer of steam like a tiny hovercraft; this is known as the Leidenfrost effect. But now, researchers know what happens when a hot droplet falls on a cool surface.

These new findings, published in the journal Newton, demonstrate that hot and burning droplets can bounce off cool surfaces, propelled by a thin layer of air that forms beneath them. This phenomenon could inspire new strategies for slowing the spread of fires and improving engine efficiency.

“We started with a very fundamental question: What will happen when a burning droplet impacts a solid surface?” says senior author Pingan Zhu of City University of Hong Kong, China.