Dear Student,
At molecular level the applied heat energy results in increased temperature forming thermal energy which makes molecules to gain momentum in terms of kinetic energy which starts to collide the other molecules results in boiling of the water. Also an phase change happens where the liquid molecule converts to trapped gas molecule which moves upward to surface layer to release vapour to the atmosphere during its track it heats up the molecules in the path. In simple terms Kinetic energy is experienced at molecular level.
Regards.