After seeing several videos of bubbles freezing, I have been trying to duplicate them. Last night, we had another cold night, down to -3°F (-19.4°C), so I tried again. I tried using more dishwashing soap and more glycerine, and got better results. Increasing the glycerine lowered the freezing point, slowing down the ice crystals. I got better results this time, but will try again with a higher concentration.