A lot can happen to a drop. That becomes evident as one reads this study, and even more evident if and as one tried to replicate the study:
“Controlled Uniform Coating from the Interplay of Marangoni Flows and Surface-Adsorbed Macromolecules,” Hyoungsoo Kim, François Boulogne, Eujin Um, Ian Jacobi, Ernie Button, and Howard A. Stone, Physical Review Letters, vol. 116, no. 12, 2016, article 124501. The authors report:
“We were motivated to pursue the ideas here from examining a whisky droplet after drying on an ordinary glass where it creates a relatively uniform particle deposit, which is in contrast to the well-known ‘coffee-ring stain’. “