When the liquid molecules are heated, they move faster so the liquid boils and some molecules becomes gas molecules. When the liquid molecules are heated, they move faster so the liquid boils and some molecules becomes gas molecules.
What do you think happens when some air heats up and other air is cool?
it heats up
evaporation
It heats up.
it heats up
One possible cause is a misadjusted brake pedal. If the push rod is pushed in slightly all the time, it will block the tiny fluid return port in the master cylinder bore, trapping fluid. As the fluid heats up and expands, it is blocked from returning to the reservoir, so it applies the brakes slightly. This heats the fluid, so it expands, applying the brakes more, which heats the fluid more, which applies the brakes more...
it heats up
It heats up
The density decreases.
You may have over filled the reservoir and the fluid will expand as it heats up and come out the cap.
It heats up and precipitates out solids.
convention current is heats by the mass movement of heat particles into an area of cooler fluid.