when water molecules get smashed, heat particles get pushed out from the oxygen and gets captured by the next water molecule's hydrogen, conducting the heat particles forward (heat particles are the particles that electrons and electron shells are made of).

so the heat particles gets conducted until they reach amino acids at the edge of the water droplet and blast out a water molecule from them, the water molecule getting smashed away as water vapour thus amino acids becomes peptide.

if the amino acid was in still water, water molecules will not get physically smashed so the heat particles conducted will be too little to smash out water from the amino acid.

if the amino acid was in the bulk rather than the edge, the heat particles gets spread out rather then focused in since there are water pulling the heat particles from everywhere while in the bulk so the heat particles gets split into smaller groups that does not have enough momentum to do much (momentum is proportionate to mass, the number of heat particles is proportionate to mass).

but in the edge, heat particles goes along the surface thus likelihood that heat particles flowing to the same point is higher, especially if the water edge is spiky due to the smashing, the spike focuses heat particles like a funnel, merging the heat particles into a bigger electron so it will have enough mass to smash a water molecule out of an amino acid.