Malicious persons could attack your ISP's DNS cache, and make www.yourbank.com
go to the IP address of their choosing instead of to your bank (and then on that other IP address run a site looking like your bank so you will disclose your password for example). While that is not unheard of for home users, you are much more likely to run into such kinds of attacks when you are browsing from an Internet cafe or using a public Wi-Fi hotspot (like in an airport or certain hipster hangouts). On a public Wi-Fi hotspot one of the other visitors can easily attack everybody else on the same Wi-Fi connection.
Storing the IP address instead of the URL is perhaps one way to reduce the risk, but it is inconvenient as IP addresses for websites can and do change over time and you won't be able to trust any website for which you have not previously fetched the IP address on a connection you thought you could trust. Like, if you do an Internet search you won't be able to trust any of the websites returned in the search results...
A better way then is to use DNS Crypt. This encrypts the DNS traffic between your computer and the DNS server, and because DNS Crypt switches from your ISP's DNS to OpenDNS you are even more secure. I have a tutorial on how to set that up here: viewtopic.php?f=42&t=107096