Generally speaking, blisters should not be popped. This is because the blisters are enclosed and they are still protecting the skin underneath from dirt and other particles. Once the blister is popped, the chance of the area getting infected goes up. If the blister does pop unintentionally, keep the area covered with some antibacterial ointment.
Also, I would recommend seeing your primary care doctor
if there is significant blistering, pain, or fever
. Sunburns can sometimes be quite serious, and any significant sunburn should probably be evaluated by your doctor to see if further treatment is needed. In the meantime, keep the skin clean and dry and take an anti inflammatory medication like ibuprofen or naprosyn for the pain and inflammation.
In the future, you will want to try to protect yourself a little better from the possibility of sunburn. Sunburns can have serious consequences, including increasing your risk of skin cancer later in life and speeding up the process of skin aging. Making sure to always where a good sun screen lotion when you are out in the sun is important, as is limiting the overall amount of time you spend in the sun.
Talk to your primary care doctor for more information.