What seemed to be a satellite, grew to full moon brilliance, faded out, then kept on trucking.

It was Monday evening, around 9pm cst.  I was facing west and looking straight up and previously noticed a satellite slowly creep in a straight line across the sky directly overhead, nothing unusual.  Being so close to Chicago, star visibility is rather poor, I can see the big dipper, some planets and a few bright stars and I have a knack for spotting satellites.  The majority (satellites) I see over time tend to travel South to North, I'll pick it up in plain site and try and follow it acoss the whole sky until it fades out of view.  The one on Monday was something I never saw before, I thought I spotted a satellite, a pinpoint of light just moving in a straight line (North to south, this time) and 2 seconds after I spotted it, it began to slowly grow in white brilliance (I immediately thought this thing was entering the atmosphere) the "glint" on this object got to be as bright as a full moon, and I noticed I had to squint it was so bright....suddenly the light contracted and continued its straight line course, returned to its normal illuminated pinpoint of light and faded out.  If this is a satellite (or ISS) it is glinting the sun in certain positions that are really gonna freak people out. Only explanation I can think of.