OG - Here's a new one for me. Where's the malt?

Been brewing for 3 years, always extract or partial mash.

Tonight I did a partial mash. I call it an XIPA, not quite a IIPA, but a strong IPA.

I did the usual, steeped 1.5lbs of specialty grains, boil 2G, put 3LB LME in at start of boil. At the end of the boil, I took the pot off of the burner, stirred in another 3lbs LME, 0.5lbs of Munich LME, and 1lbs corn sugar.

I did my usual quick cool.. Pour the wort on an ice block. Top off to 5G. Temperature is good to pitch yeast in 5 minutes or less.

But wait.... Boy does the wort look light and clear????!!!!

So I drop in the hydrometer, expecting about 1.063, get 1.015!!! Holy crap.. Look around, make sure all of my LME bottles are empty... Sugar gone. What the heck did I do wrong?

So I spray some starsan on a spatula, and stir... OG goes up to 1.030. So then I stir for a solid minute.. BOOM. 1.063.

Glad I didn't just pitch, because I rarely check OG since I have a huge extract base.

I hope the sugar doesn't just settle back on the bottom.

Maybe I should always boil the extract for a few minutes instead of adding at flameout.

Not an uncommon problem. Top off water will stratify and sit on top while denser wort settles. For an accurate OG you need to give it a good long stir. The good news is that even if you don't stir, the yeast will still find the sugar and your fermentation will be fine. Your OG measurement will just be out of whack.

It's made even worse by having that much malt extract in only 2 gallons of water. If you like IPAs and IIPA, you will greatly benefit from larger or full boils so your bitterness doesn't take such a dilution hit.

^^^^^ +1 on both of the above