A capacitor discharge system is used to rapidly heat an aluminum wire sample which is submerged in water. The heating process and subsequent explosive event are monitored. The test sample is 0.0114 g of 99.99% pure annealed aluminum. The resistive heating of the wire commonly takes on the order of 70 mu s. The results show that a flash of light occurs near the end of the current flow to the sample. When the energy deposited in the wire is less than some critical value, near 2200 J/g, the duration of the light production is typically short, around 220 mu s. However, it was found that larger energy densities result in much longer luminous events, around 700 mu s, which are interpreted as sustained combustion.