Is it possible for someone to be vaporized by pure radiation?

I don't mean with a nuclear bomb or the affects with the sun. I mean that if there was a material with an isotope that was more radioactive then you could ever imagine, would it be possible for someone too just spontaneously burst into flames or melt into a pool of destroyed cells? If there was enough radiation pulsing from a radioactive isotope, could someone or something be vaporized without being subjected to a blast of fire or heat?