Got yet another explosion, this time with heating resistor. It was ARGOL 10 ohm 25 watt heat sinked resistor, and the problem was that if i tried to go above 200 celcius, there was "explosion", with one cap of the resistor blown out.
Maybe should try to drill out the center stuff, and use resistor wire, and fill with some non-exploding cement (any suggestions what would be good cement?)