Overheating and confused

So bought this 99 328i guy says it overheats doesn't have money to fix it. I replaced thermostat,radiator,radiator cap,clutch fan.Pulled water pump spins freely looks in great shape.Put the car back together bled the system.Start the car let it warm up no issues can run for 30 minuets no problems. Take it for a test drive,drive it about a mile and you open the hood it has water coming from radiator cap.After a few minuets car then gets hot. No water out exhaust no water in oil.Any ideas....???