Clean out and remove any labels from a clear glass mason jar. An 8 ounce jar or larger, such as a pasta sauce jar, a preserves jar or any other type of mason jar is ideal.
Fill the jar with tap water so that it is 3/4 full.
Place 2 tablespoons of liquid soap into the water. Any type of liquid soap will work; hand soap, dish soap or body soap, for example.
Replace the lid on the jar. Twist the lid so that it is extremely tight.
Hold the bottom of the jar in one hand and twist it in a circular motion. As the liquid soap circles inside the jar it will mix with the water to create bubbles and form a vortex in the middle of the jar.