Sounds like you got it too hot. Try lowering the heat. Gas or electric range? The latter might be tougher to keep at a gentle enough heat.
Also, watch the water vapor, or lack of. Once it stops steaming, I myself give it a few more minutes then call it good. I think the day-long outdoor simmering affairs are for doing massive quantities. A pound or less of fat in a small pot shouldn't take that long and doesn't need a lot of fussing over.
Good luck. Or if you prefer, live and learn -- there's always next time. :-)
One other suggestion, make sure the fat has as much surface area as possible. Grinding works best. If you can't grind try 1/2 inch cubes. Use just just enough water to completely cover the bottom of the pot. You want the water to stop hot-spots from cooking the cubes until the fat has melted. The goal is a gentle, even temperature. You are trying to evaporate off the water and separate the solids without denaturing the fat.