Ah, the ol' bag in a box.  Back when I was kitchen manager of my fraternity, I used to have to deal with these a lot, and they sucked.

Basically, the way a whole lotta soda is sold, unless you buy it in a can or a bottle, is through soda fountains.  And the way most of those work is by putting a few gallons of the soda syrup in a big bag, and then putting that bag inside of a cardboard box.  You then connect lines from the fountain machine into a doodad on the bag, connect another line to a CO2 tank, and voila!  You've got yourself a soda fountain.

They're also a MAJOR PAIN IN THE ASS.  You'll usually have six boxes connected to the fountain, for six different products (regular, diet, root beer, etc.).  Originally, I'd wait until two or three boxes of syrup emptied before I'd make the trip down to the basement and lug more upstairs.  Big mistake.  If a user tried to get soda out of a line where the box was completely empty, it could cause air bubbles to come up through the lines.  I don't exactly know how or why, but this would send the CO2 tank into conniption fits.  This, in turn, would screw up your syrup to CO2 ratio, ruining all six lines.

They also leak.  Even making sure the connections are airtight, checking for holes, and cleaning the storage compartment every week, somehow the space would always be disgusting and covered with dried syrup by the next time I checked it.  God help you if you drop one of the boxes while you're carrying it...