A drop of water can skitter across a hot pan for a minute instead of boiling away

Drip water onto a pan heated well past boiling point, and instead of vanishing instantly, the droplet can dance across the surface for far longer than a drop on a merely warm pan. Johann Gottlob Leidenfrost described the effect in 1756: the pan is hot enough to instantly vaporize the droplet's underside, and that cushion of vapor insulates the rest of the drop, letting it hover almost frictionlessly. The same principle lets people briefly dip a wet hand in molten metal without being burned.

— Johann Gottlob Leidenfrost, De Aquae Communis Nonnullis Qualitatibus Tractatus — 1756