We've tried and tested many bubble mixes over the years and can categorically say this makes the best and biggest bubbles. Make the mix the night before your want to use it - it only takes ten minutes.
12 cups or 3 litres distilled water (from petrol stations)
1 cup or 250ml washing-up liquid (Fairy works well)
3-4 tbsp glycerine (from chemists or supermarkets)
Put the water in a bucket or large pan. Add the washing-up liquid and glycerine. Stir slowly so you don't form a froth (you don't want bubbles yet). Leave overnight for best results.
Use this bubble mix with the Giant Bubble Wand and you'll soon be creating bubbles up to 2m long!
Warning: bubble mix is sticky. Use outside where any marks are washed away by rain.