Pure sugar caramelizes when it hits heat (hence why caramel exists), so next time you're caramelizing an onion, don't hesitate to add a little brown sugar. You don't need much, though -- no more than ...

Add the brown sugar and salt, and remove from the heat. Add 4 cups water, and stir until the sugar and salt are dissolved. Let cool completely. Add the onions, bacon, Guinness, and 16 cups cold ...