We put milk in a plate and dropped some food colouring in it.
We put some dish washing liquid on a cotton bud and dipped it into the milk.
The colours swirled away and made patterns and rainbows. The colours kept on moving by themselves.
Why does this happen ?
The molecules of fat bend, roll, twist, and contort in all directions as the soap molecules race around to join up with the fat molecules. During all of this fat molecule gymnastics, the food coloring molecules are bumped and shoved everywhere,