What's that POP and *SPARK* about when installing a new light?

Last night my husband and I were trying to install an antique chandelier. When I purchased it, we were told that it was newly rewired. There was no ground wire. I put 5 60 watt bulbs in it. There was a newer fixture hanging where we put the chandelier and the wires appear to be newer. My husband checked to be sure that all the connections were well covered with electrical tape and wire nuts where applicable. After everything was in place, we flipped the switch. There was a POP sound and a SPARK. The lights stayed on but no longer dimmed by the switch as the old fixture had. Once the initial pop and spark happened, it didn't happen again. The circuit breaker did not trip. For right now, the light is off with tape over the switch so no one accidentally turns it back on. Any thoughts as to what this might be? Here's a pic of the light as it hangs right now: http://www.kitschykitten.com/2010/07/26/let-the-decorating-begin/ Thank you for any advice or input you may have!