gonna add my own tips 
if im cleaning the inside of a pan thats burnt on.. i just steep it in hot water and washing liquid.
10 mins or so and it should come up clean. with light scrubbing.
that being said my pans are seasoned.
so they never seem to need anything other than washing liquid and a pan scrub as the burnt on doesn’t seem to bond as well to the seasoned surface.
for them that dont know, to season a pan.
heat it up till its hot. once up to heat add a little oil (butter works best imo) that should start smoking… quickly wipe the oil around the pan with a clean lint free cloth or kitchen towel), stick back on the heat again and as soon as it starts smoking again. wipe it again. now stick it under a cold tap..
if you did it right when you stick it under the tap the water should instantly boil for a second.
now wash as normal and your done.
for the ones that still dont come up clean.
i put water in the pan to cover the burn, stick it on the heat and add washing powder.
let it boil for the next 10 mins topping up the water.
take off the heat and put it under a running tap and scrub what’s left off.
for the hob spills that burn on.
i use mostly table salt.
i lightly spritz the hob with water (not so much it puddles), with a mix of lemon juice and white vinigar.
then cover the whole thing in a layer of salt.
leave for 30 mins. spritz the salt again.. give it another 10 mins.
then use a dry pan scrub to remove the grime the salt pulls off the enamel. and gather the pile for disposal (i use a vacuum cleaner for this bit to be honest )
yeah its mancave shit, but. its a clean mancave. 