Bring a large pot of salted water to a rolling boil and add the lobsters. Cover the pot and cook for 8 to 12 minutes, until the lobsters are red and cooked through. (Because each lobster is cooking independently, base your cooking time on the size of each lobster, not their combined weight.) The lobsters should cook for about 8 minutes per pound, so adjust the time up or down based on the size of your lobsters. Use tongs to remove the lobsters from the pot and set them aside to cool.