Hard to get oil and water to mix, and stay mixed. I experience this sometimes when making hard candy. But hard candy doesn't have to sit and cool that long to finish like jello. It will try to separate as I'm pouring into the molds. My solution is to whip vigorously to mix and continue pouring. All the while racing to get done while it's still ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.