Clear evidence for the microwave effect has been observed during experiments in which a variety of materials have been heated using experimental systems that allowed both conventional and conventional-microwave hybrid heating. A hybrid single mode cavity has been used to investigate the microwave effect during phase changes in silver iodide, barium titanate and benzil, whilst a hybrid multimode cavity has been used to investigate the microwave effect during sintering and annealing of a range of ceramic materials with different dielectric properties. Although evidence for the microwave effect was not found in every case, where it was found the results could not be explained purely in terms of temperature gradients within the materials.