From Courtenay Tucker at WISN12: "Dubbed the boiling water challenge, it involves taking a mug or saucepan of boiling water outside and quickly throwing it into the air to watch it instantly transform into snow."
But how? This Live Science article is from 2011, but that's OK since the temperatures of boiling and freezing water have remained the same for a while. Mark Seeley, a climatologist at the University of Minnesota, explained, "When it's cold outside, there's hardly any water vapor present in the air, whereas boiling water emits vapor very readily that's why it's steaming," Seeley says. "When you throw the water up in the air, it breaks into much smaller droplets, so there's even more surface for water vapor to come off of..."
"You have to have a huge temperature gradient to see this effect. I'm surprised it was cold enough at minus 22. Here in Minnesota, we don't try this experiment until it's minus 30, but I suppose if the air is dry enough if it's minus 22 with extremely low relative humidity you can get away with it."
Remember, it's still boiling water, until it's not, so wear PPE and don't spill it on yourself or others. Now, go do silly stuff outside in frigid temperatures!