You can easily see for yourself how the amino acids, trying to get as far away from the water as possible, formed into little spheres or bubbles. Just take a glass of water and put it on the table. Then slowly pour in some vegetable oil.
You’ll see that the oil tries to get away from the water by making little globs or bubbles. If you let the glass alone for a little while, you’ll soon see that the oil and water separate completely, with all of the oil sitting on top of the water, like a one-layer lipid membrane.
Another thing you can do to understand lipids better is to blow soap bubbles. Soap is also made out of lipids, and it forms membranes in spheres, just like the lipid membrane bubbles on early Earth. Or, get your hands greasy with oil and then wash them with soap.
The soap is made of lipid molecules, with a water-loving end and a water-hating end. The end that hates water sticks to the oil on your hands, and the end that loves water sticks to the water, and so the lipid molecules gradually carry the oil away from your hands and into the water. See how the soap also makes bubbles?
Bibliography and further reading about lipids and cells: