Can I connect a voltage, higher that the 1.1V bandgap voltage, to an ADC pin
Yes, you can go above VRef.


  Voltage on any Pin except RESET
  
  with respect to Ground ................................-0.5V to VCC+0.5


And as the ADC reference says anything above VREF will give you the maximum value (it will saturate).

So powered from 5V you can apply anything from -0.5V to +5.5V safely. That's basically the supply voltage plus one diode drop for the ESD protection diodes within the pin.

The ADC is just comparing two voltages. The VREF isn't used to power anything.