Probably not explode. Probably just get cooked until it's bare rock. Maybe there might be a pop briefly when it falls into what remains of the sun? I don't know how energetic the emissions are when something the size of Earth falls into a white dwarf - could it be characterized as an explosion? Or, maybe over the billions of years, a rogue will pass through and pull the Earth away, and we'll escape to become a wanderer ourselves, very, very slowly evaporating and shrinking as the protons decay, until nothing is left.