A system for controlling the temperature of a reaction mixture comprises at least one heating device for heating the mixture and a power regulator for regulating the amount of power supplied to the heating device. A controller in communication with the power regulator includes program instructions for heating the reaction mixture by setting a variable target temperature that initially exceeds a desired setpoint temperature for the mixture. When the heating device reaches a threshold temperature, the variable target temperature is decreased to the desired setpoint temperature. In another embodiment, the controller includes an adaptive control program for dynamically adjusting the duration or intensity of power pulses provided to the heating device.