If you hunt any game you would know that to keep the meat longer, you'd need to gut the thing and remove its entrails. The digestive tract, or GI as med school students would call it, is sometimes considered as part of the outside of the body. There are several species of bacteria both good and bad living in the GI tract some of which are necessary for good digestion and have to be replenished with yogurt after taking strong antibiotics. After death, these bacteria are left unchecked and start breaking down the digestive system itself and creates a bloated stomach, which can sometimes explode with the right conditions.