Explosives
If you like to watch people explode, this is the bobblehead for you, permanently increasing damage with explosives by 15%.
Make your way to the far east of the map to find Saugus Ironworks.
Head inside via the courtyard full of bonfires. Be wary of the raiders here as they're kitted out with flamethrowers and will waste no time in roasting you to a crisp.
Proceed through the ironworks until you reach the blue double doors that lead to the Saugus Blast Furnace. There's a mini-boss waiting for you behind here along with Jake from the Out of the Fire quest line, so get ready to slug it out.
Once the fight is over, head up the stairs to the second level. If you want Jake to survive the encounter, sarcasm, telling him his father wants him back, or a bit of persuasion will get him on your side.
Check the panel on the back wall.
The bobblehead is on top.