Angular 2 http.post() is not sending the request

When I make a post request the angular 2 http is not sending this request

this.http.post(this.adminUsersControllerRoute, JSON.stringify(user), this.getRequestOptions())

the http post is not sent to the server but if I make the request like this

this.http.post(this.adminUsersControllerRoute, JSON.stringify(user), this.getRequestOptions()).subscribe(r=>{});

Is this intended and if it is can someone explain me why ? Or it is a bug ?