You can definitely purchase a domain name without a hosting package. However, if you wish to host the domain name on the internet, you will definitely need a hosting provider and space provided by them.
Once the hosting package is bought, all you need to do is register nameservers, assign them to the IP addresses that have been provided to you by the hosting provider.
If your hosting provider also offer domain registration, you can definitely host the domain name with them.
Regards,
Shane Phillips