Make Lava Lamp

Explanation: To begin, the oil stays above the water because the oil is lighter than the water or, more specifically, less dense than water. The oil and water do not mix because of something called “intermolecular polarity.” That term is fun to bring up in dinner conversation. Molecular polarity basically means that water molecules are attracted to other water molecules. They get along fine and can loosely bond together (drops.) This is similar to magnets that are attracted to each other. Oil molecules are attracted to other oil molecules, they get along fine as well. But the structures of the two molecules do not allow them to bond together. Of course, there’s a lot fancier scientific language to describe density and molecular polarity, but maybe now you’ll at least look at that vinegrette salad dressing in a whole new way. 

When you added the tablet piece, it sank to the bottom and started dissolving and creating a gas. As the gas bubbles rose, they took some of the colored water with them. When the blob of water reached the top, the gas escaped and down went the water. Cool, huh? By the way, you can store your “Blobs In A Bottle” with the cap on, and then anytime you want to bring it back to life, just add another tablet piece. 

Source: https://sciencebob.com/blobs-in-a-bottle-2/