Was the voltage on the other "phase" higher? It sounds like a floating neutral, this is a very dangerous situation because it can fry lot of electronics.
From my understanding, your typical home electrical transformer brings 7,200 volts from 1 phase of a 3 phase system (ground being the other end of the winding) down to 240 volts, there is a centre tap which is a neutral, and ground. At the panel they are bonded and after that they are considered different and should never be bonded again but generally will have the same voltage, 0. The two leads coming out of the transformer are called the hots or legs and are 240v between each other, and 120v to ground or neutral. A typical electrical panel has each breaker setup in a way that they feed off 1 of the two hots in a staggered way. Breaker 1 is on leg 1, breaker 2 is on leg 2, breaker 3 is on leg 1 etc. (reading order along one line of breakers) 240 volt appliances like the oven and dryer use a double pole breaker as the circuit feeds from both breakers (which share each leg, so 240 volts) while a 120v item will feed off 1 breaker and then the neutral bus bar to complete the circuit. Most 240v appliances will still have 120v stuff so there will actually be 3 wires going to them, 2 hots for 240 and a neutral for 120.
In a floating neutral situation 240v loads will work fine, but 120v loads will be in series with the loads on the other leg of the 120. The voltages will fluctuate based on the loads. Ex: one side might be 100v while the other side might be 140v.
If it was indeed a floating neutral you did well by turning off the main. Do not turn off individual items as it might change the way loads are balanced and cause further damage. To troubleshoot you'd then turn off every single breaker, open the cover off the panel and turn on the main with absolutely nothing else turned on. You could then probe around as needed.... though this would probably be something you'd leave to an electrician unless you are familiar with electrical. If you accidentally short out the live bus bar you'll be having a closed casket funeral.