Why does my pan always splatter when I make chicken breasts? I've been cooking for myself since summer started and have been pan-frying a lot of chicken breasts in Sunflower oil. They taste great, but from about halfway through, there's a TON of splattering. Even with the splatter shield it makes a mess of the stove. 

I cook them on medium, which takes about 12-14 minutes a side on my stove. Reducing the heat doesn't help much and just takes longer to finish cooking them. I've also tried adding more oil, but that doesn't prevent the splattering either.
The reason why fried meat splatters is that correct frying temperatures (~ 180 Celsius pan surface) are well above the vaporizing temperature of water (100 Celsius). Each droplet of cell plasma which comes into contact with the frying fat creates a tiny steam explosion. And explosions splatter. 

If you were meaning to ask not why it splatters, but how to prevent it: you can't. See also the existing question about it. 

On a side note, 12-14 minutes per side of chicken breast sounds like you are reducing it to particleboard. See this question for correct internal temepratures.