This can only happen on the First Day. The boulder can only be blown up by a Powder Keg, which can only be available when you are licensed to be a Powder Keg user. To be licensed, you have to have the Fire Arrows from Snowhead Dungeon to blow up a cave blocked by ice near the Goron Village. Go in the hole with the Goron mask. A big Goron known as the Instructor will test you.