Sex Machine, It is probably a combination of your stomach becoming more used to as well as using a warm liquid.
the reason your experience stomach discomfort is because dissolving creatine in regular fluid is useless. You'd be more likely to fit an elephant through a key hole. It's just not going to happen. As a result of this poor solubility, when the creatine gets to your gastrointestinal tract, the body tries to solubilize it. Why? Because nutrients cannot be absorbed if not solubilized or dissolved in a solution.
They will just sit around in the pit of your stomach in powder form and eventually pass right out of you. So what the body does to remedy this is to suck fluids out of the cells of the digestive organs in order to provide enough fluid to dissolve the creatine. But what then happens is that all this fluid that's sucked into the GI tract needs to quickly be eliminated and this leads to diarrhea. So in solubilizing your creatine, the GI causes some nasty bathroom situations. Not to mention the fact that a lot of the creatine is lost during such porcelain episodes.
By dissolving it in warm water, due to the laws of thermodynamics, the creatine is solubilized. And when consumed, it can be absorbed much more effectively without all the GI distress.
I use a warm cup of Coffee or Tea.