Punctures are usually due to running over something sharp in the road, or a spoke poking through the tube from the inside of the rim. If you examine the tube closely, you should be able to find the hole. If the puncture repeats, it's often due to a fine shard of glass or wire sticking in the tire. These can be hard to see, so most experienced cyclists will spend some time carefully running their fingers inside a tire after a flat. The goal is to find that tiny sliver before installing the new tube and flatting again a few miles down the road.
If the puncture is on the inside of the tube, that would be caused by a spoke end poking through the rim tape and into the tube. You should be able to detect that by checking the rim tape bed carefully by eye. Anyplace you see the end of the spoke cutting through the tape is trouble.
If you've literally had "blowouts", that indicates the tube has blown out of the tire because the tire bead seperated from the rim. A blowout would look like major damage to the tube on it's side, much different than a puncture hole. It could be caused by excessive pressure, but also by mismatched tires and rims, wornout rims, or old or poor-quality tires.
Most of us consider a "blowout" on the front tire to be a dangerous scenario, particularly on fast descents. If this is indeed what you've experienced, I'd say a trip to your LBS mechanic is the smart thing to do. You may need to invest in some new tires, or new tires and new rims, but regardless of the cost, your safety is worth getting it sorted.
