Suddenly, Goyle's potion exploded, showering the whole class. People shrieked as splashes of the Swelling Solution hit them. Malfoy got a faceful and his nose began to swell like a balloon; Goyle blundered around, his hands over his eyes, which had expanded to the size of a dinner plate - Snape was trying to restore calm and find out what had happened. Hermione had erected a shield around herself, but was looking around suspiciously. Greg was actually good at Potions, so what happened?