Surely, you have observed how sometimes streaks “hang” from under the clouds - this is a so-called virga, which can appear under cumulonimbus clouds.
This is the same rain, but it evaporates before reaching the surface of the earth. The reason for this is low ambient humidity. That is, dry air in the way of drops tends to saturate with moisture and "absorbs" them.
So the rain simply evaporates on the way to the earth. Due to the evaporation, the surrounding air becomes colder - a cold air mass goes down and suppresses new air flows rising under the cloud. This becomes the main reason for the cessation of the growth of the cumulonimbus cloud, and it is destroyed.
Read more meteo lessons in Windy.app Textbook.