A gigantic solar storm has been detected and recorded on video. Watch the video and commentary here.
The sun is a strange object. It is basically a huge ball of plasma, which is an electrically charged fluid. Understanding the behavior of fluids is hard enough, but when you have this much of one with a constantly changing magnetic field, it becomes a nightmare to predict.
All this goes to show that even after centuries of study, we are not really sure how the sun works, and have essentially no ability to predict its future behavior.