A friend of mine who helped me brew did this part for me when we were doing our first batch of beer. I’m not sure how much sugar he boiled prior to bottling. It was an all extract kit (regular 5 gallons).
What is the normal proportion for priming sugar to wort?
The amount of carbonation you want will change the amount you use (eg. a low carbonated stout or a high carbonated wheat ) 3/4 is a great general amount. I have gone as little as 1/2, a little too flat for me. And as high as 1 cup ( not sure I recomend that one. I think I almost had grenades.)
When you say that you “almost had grenades” you mean that if you put too much sugar in then bottled, the bottles almost exploded during the carbonation period? (too much pressure?)
You need to make sure your fermentation is done and that your beer is fully attenuated before priming and bottling. All that residual sugar is food for the yeast, which will make carbon dioxide. No place for it to go, carbonation. More carbonation (i.e., pressure) than the bottle can handle, boom.
Most of brewing is about avoiding things that go boom. Take my word on that one.
It might be a good idea to weigh the sugar first. Just to get an idea of what you’re dealing with.
There are online calculators that can tell you per volume of beer which amount of sugar to use to achieve the volumes of co2 for the style you have brewed. Http://www.tastybrew.com/calculators