Over the two previous days oil fell $10.50 a barrel. By definition this is driven by news about supply and demand but has so much news come out so quickly?
Here are two ways to think about the mechanisms at work. First, some producers could supply more but they figure that China will be buying more tomorrow so maybe it is better to wait. If they see a signal that future global demand will be lower, they are less likely to let oil sit in the ground. In other words the market develops the expectation — true or not — that oil supply will rise more rapidly than had been thought (or "decline less rapidly" may in some cases be a more accurate phrase but the net direction of the effect is the same). Lower expected demand is thus paired with greater expected supply and that tends to make price volatile. Higher expected demand is paired with lower expected supply in similar fashion. noting in either case that you can make lots of different assumptions about the relative timing of the expected changes.
Second, any new information leads to more trading and to more trading at different ranges of price and quantity. This trading reveals more information about the elasticities of market supply and demand curves and that information in turn feeds back into the market price. In a nutshell, some initial price and quantity movements lead to further price and quantity movements.
Neither of these phenomenon are correctly called "bubbles" but neither do they fit the story where the price of oil is determined by fundamentals alone. "Expectations" is a central word here, noting that only time will tell whether or not the expectations are rooted in reality or not.