Carsten said:
Oren, the first picture with the cows around the glass of milk is probably one of my favorite pictures in the world.
Turn regular milk into a magical piece of art!
This experiment is adapted from the one by Anne Marie Helmenstine, found at About.com.
Materials:

The experiment:
1. Pour the milk into the plate. Make sure it covers the entire plate, and that the plate is clean and dry before you use it.
2. Place a few drops of food colouring around the milk in different spots. Be creative! This is your chance to create real art.
3. Dip the cotton swab in dish detergent.
4. Ready? Set?... Go! Touch the milk with the dish detergent swab. You can place it at the centre of the plate, or see what happens when you put it in one side! You don’t have to stir or move the swab at all, just sit back and watch the magic.
What’s going to happen: (Spoiler alert!) The food colouring will start to swirl and move in different directions, and the once-white milk will become a magnificent, colourful artwork. Cool!

You can watch a video of the experiment right here!
The chemistry behind the scenes:
Milk is a homogeneous mixture of many chemical substances, elements and compounds. Among these you will find proteins, which are natural compounds found in food and in your body, fats, which are also found in food and in the body and are generally soluble in organic compounds but not in water, calcium (Ca, element #20), and other cool milky stuff.

Dish detergents are chemicals designed specifically to clean your plate of food. They contain phosphates, which are compounds that have phosphorus and can dissolve calcium, and various enzymes that break down proteins and fats to smaller particles that can be easily washed away with water. Detergents also contain chemicals called surfactants, which lower the surface tension of a liquid and allow easier spreading.
When we add food colouring to the milk, nothing happens. BUT, when the dish detergent touches the milk, things start to move. The surfactants reduce surface tension, which allows the food colouring to spread around the milk. Then the enzymes start to react with the calcium, proteins and fats in the milk, which causes the colour pigments from the food colouring to get pushed around, resulting in a cool colourful pattern.

So you see, it’s not magic. It’s chemistry!
Chemistry is cool!