There are hundreds of web pages describing recipes for giant soap bubbles. Some of the more interesting ones are The Bubblesphere, Bubble Town, Soap Bubbler, Riesenseifenblasen durch polymere Additive (in German), Nanotech Kids. Why another web posting about soap bubbles? Because almost all of them use ingredients that are not available where I live (i.e. Finland). I got a recipe from a soap bubbler who performed at a kindergarden event in my neighbourhood and here is my modified version (including brand names which were absent from the original recipe):
In a clean pot you boil the 1000 ml of the water, switch off the heat and mix in the sugar until it is completely dissolved. Then you let the mix cool down to room temperature. In the meantime you dissolve 3 g of the wallpaper paste into the rest of the water (200 ml). Let the mixture stand for 15 minutes and mix again. Its consistency will be like jam. Then mix 160 ml of Fairy Sensitive and the dissolved wallpaper paste into the sugar water. Mix well and let stand in the fridge over night.
I have not yet tried to improve the longevity and size of the bubbles by using additives, but I am thinking about adding (or replacing some of the water by) glycerol, polyvinyl alcohol (PVA) or linseed oil.
In addition to the solution it is also very important to have the correct device to produce giant bubbles. I bend a piece of strong wire into a loop and attach a wooden handle, then I take a gauze bandage and wrap it very tightly several times around the wire to hold lots of the solution.
For some protein refolding experiments I tested dioctyl sulfosuccinate as detergent. I needed only 100mg, and I used some of the stuff to make super-large soap bubbles. Here's the recipe I used: