There are different opinions about that. Some people stick to the absolute answer that ingesting a single calorie means you’ve broken your fast.Others will say that consuming less than 50 calories will not disrupt the fasting state of your body because it hasn’t reached a threshold to switch from fat burning to food burning.
As for suddenly feeling very hungry, it may be that tasting something sweet triggered your brain by sending it a signal that calories are on the way. But nope, not really!