To take photos of frozen bubbles, temperatures must be below freezing. I like to shoot them with temps in the teens. Colder temperatures will work, but the crystals form quickly. With slightly warmer temperatures you have more time to focus and get the shot you want. It is also important that there is no breeze as wind will pop the bubble.
If you have difficulty getting the bubble to stay put, try daubing a bit of your bubble solution on the spot where you want the bubble to sit. Let it freeze slightly and then use a straw to blow a bubble on the spot. I find that holding the straw so that it is nearly vertical works best, as the bubble mixture will drip out of the straw if it is held horizontal.
Go ahead and have some fun. Each bubble is different. You may see ferns, stars or other shapes as the crystals form.