Hot material near Earth's surface is more dense and sinks, and when it cools, it becomes less dense and rises.
Explanation:
Convection is a process by which less dense material rises and more dense material sinks near Earth's surface. Water, air, rocks and other materials expands when temperature rises and they become less dense. When the water is heated it becomes vapors and carries away thermal energy from the water.
evaporating some of the water contained in the solution will increase the concentration of the resulting solution, because there will be concomitant increase in the number of moles of the solute left in the solution.
