UPDATE: Looks like I rushed this post this morning (read the reader comments below). Apologies.
Not 100 percent sure what we're looking at here, but our old friend Mike sent us this picture of a diesel-powered tractor having a bit of engine trouble during a tractor pull last weekend in the Netherlands. He believes this explosion has all the hallmarks of a nitrous blast, as in the diesel motor got too much nitrous in it. It might be propane, but he's pretty sure it's nitrous. There is a video of the fire at Tractorpulling.nl. Find "filmpjes" under the multimedia section on the left and then click on the video that says "European Maid." Or just click past the jump to see a video from YouTube. As you can see, the driver walks away, so I'll assume there were no injuries. The ex-tractor here was called the European Maid, by the way. If you like images of the blast, click here for more.