You may have the start of a head gasket leak causing coolant to enter a cylinder under high-load conditions. As soon as the exhaust and catalytic converter get very hot, the water may vaporize completely and stop showing up as white smoke. The coolant (ethylene glycol) will solidify and form deposits on front of the catalyst, eventually causing it to overheat and melt down. Have it tested for the head gasket leak first.
Chino Autotech Inc.