If your question relates to the nozzle, we don't recommend doing this because if left in boiling water too long or done repeated it may affect the performance of the nozzle's “slow-flow” tip. There is a fairly simple method for sterilizing it however, one that can eliminate odors also (something that boiling doesn’t always do).
First, wash the nozzle thoroughly with soap and warm water. Run the soapy water through the nozzle (pinch the tip so the valve opens). Find a small bowl or small glass food storage container (something that’s long enough to put the nozzle into, but not so large that it has a big volume to it). You want to be able to completely submerge the nozzle in this container. Make a 50-50 mixture of 3% Hydrogen peroxide (available at drug and grocery stores) and water and stir well. Immerse the nozzle in the solution, pinch the tip to make sure liquid is inside the nozzle (this assures the inside of the nozzle is sanitized and also prevents the nozzle from floating). Soak for two hours.
Rinse well and allow it to air dry. The nozzle is now sanitized and odorless.
PS If you don’t have any kind of container that will work, a ziplock baggy can be used in a pinch. Just remember to attend to it periodically, agitating it to make sure the entire surface area of the nozzle remains wet.