The motion of the rolling boil allowed me to put a metal coffee filter at the bottom of the cup and cook the coffee in the cup with the rolling boiling water agitating the grounds enough to make a great tasting cup of coffee.

With a digital thermometer, I measured the temperature of the water on the surface at a rolling boil at about 198 degrees F, but I'm at high altitude (about 5100').

Takes 10-12 oz of water to a rolling boil in five to six minutes

The water started to get hot in a minute, very hot in 3 minutes, and rolling boil in 7 minutes

The water maintains a rolling boil once the water boils.

And if you fill it at the upper end of the limit, the cup is a bit over-full and tents to splash out a few spots of water when reaching a rolling boil.