In my experience, doing 3-6 reps is the sweet spot for this type of training. As this is done in a circuit fashion with incomplete rest, you'll be unable to perform the same loads as during traditional lifting sessions.
The water on your body changes to a gas called water vapor. Water turns into a gas through a process called evaporation. Heat makes water evaporate faster. All air has some water vapor. Tropical rain forests and deserts are both hot.
As liquid water is heated, the rate of evaporation increases producing more vapor that in turn increases vapor pressure. Air pressure from above slows down evaporation of water by pressing down on the surface of the liquid. As more water vapor forms, it pushes back against atmospheric pressure.