Janne is onto it = "solvent partition." Long-standing chem lab trick to get things to dissolve.
I get that dried grease spatter on the back of my stove too. Also on the exhaust fan hood above the stove.
Dish detergent and hot water takes forever.
So, I wipe down all the surfaces with vegetable oil. Let this sit 15-20 minutes. The oil mixes with the greasy gunk.
Now, the veg oil is the carrier for the greasy crud and dish detergent and hot water dissolves all of it.