Just bought one of these for cooking on the trail, and this will be the first time using it. I read that it should take about 3 mins to boil 16 oz of water, I had 12 oz in a SS mug and it was over 10 min before it started the small bubbles before boiling. Do I need to turn the flames up higher, they were already coming up the sides. Any one with experience with these stoves, Help?