Big bubble solution: 1 cup dish soap (Dawn Original or Joy Non-Ultra is recommended), 16 cups water, 2 tablespoons baking powder (not baking soda). Let it sit overnight for the best effect.
Gigantic bubble solution: Make big bubble solution and also add 2 tablespoons glycerin, and 1/2 tablespoon J-lube powder. This solution is by far better to use with bubble wands.