There's a rather impressive video clip making the rounds showing Mount Tavurvur, a volcano in Papua New Guinea, erupting suddenly on August 29th, 2014.
You can read more about the eruption here.
What I found intriguing about that video clip is the insight it provides into the much bigger incident at Mount St. Helens in Washington state during its 1980 eruption. It was on a much larger scale (sparked by what Wikipedia calls 'the largest landslide ever recorded') but displayed the same sudden explosive release of pressure. Here's a video clip analyzing the only photographs of that eruption, putting them together in a time-lapse display.
Looking at that time-lapse video, and comparing it to the much smaller explosion at Mount Tarvurvur, one can imagine how very suddenly events unfolded at Mount St. Helens and why the damage spread so far, so quickly. It somehow makes the events of 1980 more real to me.