Movie S3.

Single-crystal growth from a levitated KDP solution. Initially unsaturated KDP solution drop is levitated, and its solute concentration progressively increases via evaporation. Once the degree of supersaturation exceeds S = 1, a crystal growth becomes possible. When a crystal seed forms, it subsequently falls to the bottom of the droplet due to gravity and proceeds to grow as a single crystal. Well-defined crystal edges are observed in the solution drop.