Physicist at a Georgia University have created a recipe for blowing enormous bubbles.
The secret lies in something called polymers, molecular strands than bind things together. In bubbles, you need polymers that can stretch without breaking from stress.
After many tests, the physicists decided that a specific combination of water, Dawn Professional Detergent, guar powder (a food thickener), rubbing alcohol, and baking powder will yield you the right polymers and some spectacularly large bubbles.
For the full recipe and story, read Ars Technica's article.