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Twink_Ass_Bitch t1_iyi2t29 wrote

What you're describing is the Leidenfrost effect. When a liquid is in contact with a surface is that much higher than that liquid's boiling point, the liquid closest to the hot surface gets vaporized rapidly and that gas phase provides a cushion/barrier between the bulk liquid and the hot surface. It's not quite accurate to describe the hot metal surface as hydrophobic, but water will bead up similar to being on a hydrophobic surface.

The beading up is because water has strong cohesive forces and if the surface a droplet is in contact with isn't stronger than that cohesive force, either because water can't touch it as in the Leidenfrost effect or if it's hydrophobic, then the droplet will pull in on itself and try to be as spherical as possible. Gravity on Earth stops it from becoming a perfect sphere so that bead shape is the best it can do.

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